The present invention relates to an improved adjustable vane centrifugal pump impeller.
By way of background, in certain applications it is desirable to have an adjustable vane impeller for use with a centrifugal pump. In this manner, the characteristics of the impeller may be changed to meet varying field requirements so that maximum pump efficiency can be obtained. In the past, the adjustability of impellers for centrifugal pumps has been effected by the use of relatively complex linkages or expensive constructions. For example, in U.S. Pat. No. 2,950,686, the adjustability of air foil sections was effected by means of an annular ring coupled to the blades through an intermediate linkage, which rendered the structure relatively complex, as was the case with the subject matter of U.S. Pat. No. 2,687,280. In U.S. Pat. Nos. 2,361,007 and 2,671,635 a central ring gear was utilized to rotate a plurality of pinions simultaneously, with each of the pinions mounting a blade, and each of these constructions was also relatively complex and expensive. In U.S. Pat. No. 2,719,000 an adjustable bladed impeller is disclosed wherein the blades adjust their position in use against the bias of a spring member, as is the case in U.S. Pat. No. 1,445,402. In addition, in all of the prior patents there was limited contact between the various parts, as through pins or gear and pinion connections, rather than the full face-to-face contact of the present invention, as described in detail hereafter. Thus, none of the prior patents disclose a relatively simple attachment construction for mounting the vanes of a centrifugal impeller on a hub in an extremely simple, expedient and dependable manner.